According to 3rd Generation Partnership Project 2 (3GPP2) standards, a Code Division Multiple Access (CDMA) system and a High Rate Packet Data (HRPD) system adopt two relatively independent networking architectures, respectively. FIG. 1 shows a diagram illustrating the networking architectures of a CDMA2000 1x system and an HRPD system. As shown in FIG. 1, the two network systems share no more interworking interface besides a Packet Data Service Node (PDSN).
The HRPD protocol defines that a voice service has the highest priority. Therefore a dual-mode terminal supporting both a CDMA network and an HRPD network must at the same time be able to answer a voice paging from the CDMA network while carrying out a data service in the HRPD network. Thus, when the dual-mode terminal is activated in the HRPD network, the dual-mode terminal has to switch to the CDMA network periodically according to a paging interval of the CDMA network to intercept a paging message on a paging channel of the CDMA network. If a paging message is intercepted, the data service in the HRPD network is switched to an HRPD Dormant state of the HRPD network, and the dual-mode terminal is switched to the CDMA network to establish a forward/reverse service channel. After that, the network side sends calling party information through the established service channel to the dual-mode terminal, and the dual-mode terminal provides the calling party information to the user. If the user answers the call, a Page Response message will be returned to the CDMA network side and the subsequent network initial call procedure will be performed. If the user does not answer the call, the dual-mode terminal will return to the HRPD network and re-activate the data service in the HRPD Dormant state.
The switching between the CDMA network and the HRPD network results in discontinuity of a service and at the same time, a long time switching process may interrupt data services having high demands for real-time performance, such as a Voice Over Internet Protocol (VoIP), a video phone, a Push to Talk (PTT) and a stream media, in a switching process. Therefore, the user's service experience is adversely affected. Moreover, a frequent switching and searching between two networks makes the dual-mode terminal an energy-hungry device.
As shown in FIG. 2, to solve the above problems, a function of forwarding a message of the CDMA network, such as a paging message, a short message and a system message, through the HRPD network is added to the air interface of the HRPD network, and the function is expanded to receive a paging message from the HRPD network when a service is carried out in the CDMA network. Meanwhile, a mechanism of HRPD-CDMA forwarding a paging message to each other is introduced to a transmit interface. In other words, an InterWorking Solution (IWS) for forwarding a paging message is added between a Mobile Switching Controller (MSC) and an access functional entity of the HRPD. The access functional entity of the HRPD refers to an HRPD Packet Control Function (PCF)/Access Network (AN). In this solution, the HRPD PCF/AN is managed as a Base Station Controller (BSC) of the CDMA network and the MSC maintains location areas of the two networks at the same time. A dual-mode terminal needs to register a location area of the CDMA network through a location area code update message in the MSC when residing in the HRPD network. The flow chart of communication of the dual-mode terminal in this architecture is shown in FIG. 3 and the specific blocks are as follows.
In block 301: when receiving a paging message from the network side, the MSC sends two messages, a Paging Request message and a Feature Notification message. The feature Notification message carries calling party information to the dual-mode terminal via the IWS, the HRPD PCF/AN, respectively, in sequence, and sends a Paging Request message to a Base Station System (BSS) of the CDMA network at the same time.
In block 302: the dual-mode terminal starts a timer to wait for the subsequent Feature Notification message after receiving the Paging Request message, and returns a response message to the HRPN PCF/AN after receiving the Feature Notification message.
If the timer of the dual-mode terminal passes a time threshold, the dual-mode terminal will no longer wait for the Feature Notification message, and the dual-mode terminal will switch to the CDMA network directly and return a Paging Response message.
In block 303: the dual-mode terminal provides the calling party information carried in the Feature Notification message to a receiving user, and the receiving user chooses whether to answer the voice paging.
In block 304: the dual-mode terminal determines whether the receiving user answers the voice paging. If the receiving user answers the voice paging, the dual-mode terminal switches to a data service which is being performed to the HRPD Dormant state, switches to the CDMA network and returns a Page Response message to the BSS. If the receiving user doesn't answer the voice paging, the dual-mode terminal keeps carrying out the data service in the HRPD network.
As can be seen from the above descriptions, in the method shown in FIG. 3, the dual-mode terminal does not need to search a message frequently in the two networks but the dual-mode terminal needs to deal with two messages, that is, a Paging Request message and a Feature Notification message, and the processing is relatively complex. Furthermore, if the Feature Notification message does not arrive in time after the Paging Request message is received, the subsequent processing cannot be performed until the timer passes a time threshold, and as a result, the time of processing is extended.